Incandescent electric lamp



March 4, 1930. 11. A. HEANY 1,749,136

INCANDESCENT ELECTRIC LAME' @riginal Filed July 3, 1916 @2 fvg-f4 Patented Mar. 4, 1930 UNITED STATES PATENT OFFICE JOHN ALLEN HEANY, OF NEW HAVEN, CONNECTICUT, ASSIGNOR T SIRIAN LAMP COMPANY, OF NEWARK, NEW JERSEY, A CORPORATION OF DELAWARE IN CANDESCEN T ELECTRIC LAMP Application filed July 8, 1916, Serial N0. 107,367. Renewed April 18, 1924.

This invention relates to incandescent electric lamps and has for its object to provide an improved lamp which is highly efficient and has an unusually long life. 'lhis is accomplished by constructing the gloWer in the novel manner hereinafter described, and by causing the glower to operate in an inert gaseous medium, such as nitrogen, or the like.

According to the present invention, the

glower is made relatively short, but of unusually large diameter for the purpose of reducing the convection losses. However, in making the glower of sufficient diameter to reduce the convection losses, the strength of the gloWer and the necessary resistivity to produce the proper degree of incandescence are not sacrificed, for, as will hereinafter appear, the glower is so constructed that it possesses great strength at the operating temperature and is capable of reaching a high degree of incandescence, even in the small size lamps and on relatively low voltages.

In its preferred form, the glower comprises a resistor, preferably of tungsten, or tungsten 25 alloy, and a support preferably composed of a highly refractory material, such as a rare oxide, or a mixture of rare oxides Which possess great strength at the operating temperature. The resistor is so associated With the support that the former heats the latter to incandescence. As Will hereinafter appear, the resistor may also act as the radiating surface and may, therefore, be in the nature of a helical coil Wound upon the support, or the resistor proper may be embedded in the support, and an additional radiating surface may be provided, preferably composed of tungsten or tungsten alloy, so that in either instance, the radiating surface is composed of tungsten or a tungsten alloy. In any case, the support of refractory compound, together With the resistor and the additional radiating surface, when one is employed', are so associated as to form a gloWer which is relatively short, but of unusually large diameter to reduce the convection losses. It has been'proved in practice that the convection losses from glowers of small diameter are much greater proportionally than from gloWers of large diameter, "9 and it is for this reason that the glower, in accordance with the present invention, is given the size and shape herein disclosed. The convection losses are also dependent to some extent upon the nature of the medium in which the glower operates and in order to further increase the efficiency and life of the lamp, the gloWer is made to operate in an inert gaseous medium of loW thermal conductivity, such as nitrogen, mercury vapor, helium, or argon. Furthermore, as the present lamp may be operated at higher temperatures than heretofore contemplated, it is essential for this reason also that the gloWer operate in an 1nert gaseous medium to reduce evaporation of the gloWer.

The .invention is illustrated in the accompanying drawing, in which Fig. 1 is a front elevation of the improved lamp; and

Figs. 2 to 5, inclusive, are vertical longitudinal sections of four different forms of the gloWer.

Referring first to Fig. 1, it will be seen that the. lamp comprises the usual glass bulb 1, which may be made of any suitable shape. The threaded metallic base 2 is associated Wlth the bulb 1 in the usual manner, and is electrically connected to the two lead Wires 3 and 4. The gloWer proper is shown at A and 1s supported in the bulb 1 by means of the Wires 3 and 4, in any suitable manner which Will tend to reduce the conduction losses through the lead Wires.

The detailed construction of the gloWer A is illustrated in Figs. 2 to 5, inclusive. In the form of the glower shown in Fig. 2, a support a is employed upon Which is Wound the resistor coil Z). As above stated, the resistor b is preferably made of tungsten or tungsten alloy and the support a is preferably made of any refractory material of loW conductivity and Which is capable of being effectively heated to incandescence by means of the tungsten resistor. Preferably, the support a is made of a rare oxide or a mixture of rare oxides, such as thoria, zirconia, magnesia, or the like. It is obvious that any one of these oxides may be used by itself, several may be used in a mixture, or one or more may be mixed with a refractory formed in a different manner.

metal, such as tungsten. Preferably, however, the support is made of thorium oxide.

The coil of tungsten wireb is wound u on the support a with the coils positione as closel as possible without short-circuiting. It wi l be noted that in this form of the glower, the tungsten coil acts not only as a resistor to heat the support 1 t o incandescence, but also acts as the radiating surface.

It may bedesirable, in some instances, to provide a radiating surface which is separate and distinct from the resistor proper. This may be accomplished as show n in Fig. 3 by providing the tungsten coil with two layers, the inner layer b1 of which is embedded in the refractory support a', and the outer layer bz of which is at least partly exposed. 'Ihese two layers of coils are connected in series. so that the current traverses both layers of coils, but the inner layer b1 being embedded in the support of refractory compound, serves'as a resistor to heat the support and the exposed surfaces of the outer layer of coils b2 constitute the radiating surface for the glower.

In the modification of Fig. 4, the tungsten coil b', or the resistor, is completely embedded in the support a. The radiating surface is formed by applying to the support a, a coat ing c of tungsten, carbon or similar material which radiates a large amount of energy per unit of surface area at a given temperature.

In Fig. 5, the lower is constructed s omewhat similar to ie glower shown in Fig. 4, except that the resistor coil of tungsten is In this forni of the glower, the support a!" is similar the support shown in Fig. 4, except that it is provided with a helical groove d which is filled with tungsten or a tungsten alloy to produce in effect a coil b. The current 1n traversin the successive turns of tungsten lying in t e helical groove d heats the su port a" to incandescence. A radiating sur ace c which may be similar in all respects to the radiating surface shown in Fig. 4 maybe applied to the support, so that the operation of the glower illustrated in Fig. is substantially identical with that shown in Fig. 4.

It will now be noted that in all of the forms of the glower herein disclosed, a resistor is employed, preferably made. of tungsten or a tungsten alloy. The lampmay, therefore, be operated at very high temperatures. It is a well recognized fact that the higher the temperature at which a lamp is operated, the greater will be the elliciency of the lamp. This high temperature at which the lamp is operated and the large diameter of the glower do not, however, tend to detrimentally affect the glower, for the support of refractory compound possesses greatstrength vat the operating temperature. The glower is, therefore, not only immune to damage when the lam; is not burning, but may be safely operate at high temperatures without danger of injury to the glower.

As above stated, the glower is operated in an inert gaseous medium, such as, nitrogen, mercur vapor, helium, argon, or any gas which iiasl low thermal conductivity to assist in reducing convection losses and which will prevent t0 as great an extent as possible, evaporation of the glower, even at the high temperatures at which the glower is capable of operating.

It has heretofore been attempted to reduce the convection losses by the use of a coiled filament of relatively large diameter, but the diameter of the coil could not be made as large as desirable t0 materially decrease the convection losses without materially weakening the strength of the filament. Furthermore, in such a type of lamp, the relatively large and hence weak filament coil prohibited operation of the lamp at high temperatures. In the present instance, the entire glower is of sufficient diameter to materially decrease the convection losses and the strength of the glower instead of being decreased by being made lar e in diameter is materially increased. he diameter of the lower is not limited by strength, and, there ore, any diameter which will allow of the specified watage from the consequent surface may be use All of thev forms of the glower herein disclosed have a radiating surface composed of a material which will radiatea large amount of energy per unit of surface area at a given temperature. The resistor in each of the glowers herein disclosed, whether the same be embedded in the suplport as in Figs. 3, 4 and 52 or surrounding t e support as in Fig. 2, being made of tungsten or tungsten alloy has a high specific resistance at the operating temperature, has a high melting point, and a very low va or density at the operating temperature. he support being made of one or more rare oxides or a mixture of the saine with tungsten or other refractory metal'possesses great strength at the operatin temperature.

It wil? now be seen that by constructing the glower in the manner described above, it may be .made relatively short and of unusually large diameter, thereb not only decreasing the convection losses, ut insuring durability and strength, even at the highest operating temperatures. The coin osition of the glower permits it to be ma e of large diameter without reducing its resistance below that required for a high degree of incandescence. The atmosphere of inert gas in which the glower operates materially assists in bringing about the results striven for in makin the glower in the novel manner describe and, therefore, the specific construction of the glower and the medium Vin which it operates are both responsible for the marked results produced by the present lamp.

It is obvious that the glower may be coni structed in various other different Ways Without departing from the scope of the invention, as defined in the following claims.

What claim is l. A glower for incandescent electric llamps comprising a resistor containing tungsten, a support of refractory compound in intimate contact With the resistor and capable of being heated to incandescence thereby, and a radiating surface associated with the gloWer composed of tungsten.

2. A gloWer for incandescent electric lamps comprising a support ofV refractory compound and a coil of tungsten Wound upon said support, said coil having an inner layer of turns embedded in the refractory compound to act as a heater, and an outer layer ofturns which are at least partly eX- posed to act as a radiating surface.

3. An illuminantffor incandescent electric lamps, comprisin a relatively short largediameter body jo refractory material, a radiating element of hi hly refractory metal encompassing said bo and a resistor coil emldded in said body and in series therewit 4. An illuminant for incandescent electric lamps, comprising a relatively short largediameter body 'of refractory material, a radiating coil of tungsten containing metal encompassing said body, and a resistor coil embedded in said body and in series electrically with said radiating coil.

In testimony whereof I aliX my signature.

JOHN ALLEN HEAN Y. 

